Operating agricultural vehicle such as tractors and harvesters often requires highly repetitive operations. Due to the repetitive nature of the work, and irregularities in the terrain, gaps and overlaps in the rows of crops can occur. This can result in damaged crops, overplanting, or reduced yield per acre. Additionally, it is often desirable for a vehicle to follow a set path pattern over an area, for example when planting a field, conducting a search, or to reproduce a previously created path pattern at a later date. For example, a field may be ploughed, then sowed or planted, fertilized, sprayed and harvested. Following the same path pattern over the field each time ensures that each subsequent action is targeted to the correct area. It is therefore advantageous to pre-plan the paths that a vehicle will follow. As the size of agricultural vehicles and farming implements continues to increase, precisely controlling their motion becomes more important.
Guidance systems are increasingly used for controlling agricultural and environmental management equipment and operations such as road side spraying, road salting, and snow plowing where following a previously defined route is desirable. This allows more precise control of the vehicles than is typically realized than if the vehicle is steered by a human.
Projected paths may be used to guide a vehicle directly, or transmitted to an on-board display to be followed by a human operator. Systems of course-correction may be used to minimize cross-track and offset if the vehicle deviates from a pre-projected path. Gain tuning may also be applied to the auto-steering system in order to approximate the differences in human steering when the vehicle is traveling at different speeds.
There exist current systems for pre-planning the path of a vehicle. However, the produced set of paths are often disjointed. Typically, at the end of each path, a driver must disengage the auto-drive, manually direct the vehicle to the next path to be driven and line up the vehicle with the new path.
Known methods of steering an agricultural vehicle may include selecting a desired position and heading and calculating a desired radius of curvature to arrive at the desired track with a desired heading. This system is real time feedback system, which takes into account the contours of the surface and continually corrects the course of the vehicle.
Another method is to use a vision based system of automated vehicle steering. An electromagnetic sensor is used to gather information about field characteristics, and plan a trajectory. This includes determining points in the path matrix the vehicle will be guided towards and determining the desired wheel angle required such that the vehicle origin will pass through that point, given the vehicle's position relative to that point and the turning radius.
It is also known to pre-determine entrance points and advance points on a pre-planned path, but the means of planning an appropriate path between points on a pre-planned path or set of paths has not been discussed.